bulldog front loader

coppertop1 · Aug 21, 2020

Hey folks, I have a Mitsubishi tractor with a Bulldog 285 front loader on it. I had the boom cylinders rebuilt not too many hours ago and they did fine..until last week. Now the bucket leaks down fairly quickly. The bucket will pick up and hold the front of the tractor off the ground when I press the bucket down. I thought if just one cylinder was bypassing the good cylinder would still hold the empty bucket. Think maybe its an O ring in the valve body? Any ideas? Thanks

Dave M7040 · Aug 21, 2020

coppertop1 said:
Hey folks, I have a Mitsubishi tractor with a Bulldog 285 front loader on it. I had the boom cylinders rebuilt not too many hours ago and they did fine..until last week. Now the bucket leaks down fairly quickly. The bucket will pick up and hold the front of the tractor off the ground when I press the bucket down. I thought if just one cylinder was bypassing the good cylinder would still hold the empty bucket. Think maybe its an O ring in the valve body? Any ideas? Thanks

Rarely is it the valve. Typically the valve bore and its spool are fitted to such close tolerances ordinary mechanics can not measure the clearance.

It is this tight tolerance which prevents leakage.

Swap the lift arm hoses for the bucket hoses and see if the problem persists. If so then the problem is in the cylinder(s).

Disconnect and cap the hoses for one bucket cylinder so that you are observing the performance of only one cylinder.

There are more complicated but accurate double acting cylinder tests as I will post below.

Dave M7040